Process and apparatus for heating coal and other like furnaces



Feb. 18, 1930. w. scHAEFER El AL b 3 PROCESS AND APPARATUS FOR HEATING COAL AND OIHER LIKE FURNACES Filed Oct. 26. 1926 INVENNM Patented Feb. 18, 1930 UNITED STATES WILHELM SCHAEFER AND WALTER IOHL,

OFDRESIJEN-A, GERMANY, AssIGNoRs 'ro KERAMISCHE INDUSTRIE-IBEDARFS AKTIENGESELLSGHAFT, 0F DRESDEN, GERMANY PROCESS AND APPARATUS FOR HEATING GOAL AND OTHERLIKE FURNACES Application filed October 26, 1926, Serial No.

For heating so-called tunnel-furnaces it is known to employ pre-heated combustion air at the several places of combustion and also to regulate the supply of pre-heated air.

By the process according to this invention it will be possible to regulate also the temperature of the combustion air to be supplied to the furnace in any desired manner. For regulating the temperature of the combustion air the following principles form the basis of this invention: When supplying cold or only slightly pre-heated combustion air to a stream of gas of a definite temperature, the mixture will undergo combustion and produce a long flame, that is to say the com- 7 bustion in this case is only completed after a definite time and after a definite way of travel. WVhen supplying very hot combustion air of a definite temperature into the stream of gas, the time and the way will become so short, that the combustion will at once take place at the same time producing a very thin or pointed flame. I

By the process according to this invention it will be possible to mix the combustion air at an exactly adjustable temperature,*which depends upon the composition and temperature of the gas stream, with the burning gases in the furnace on their way into the interior of the latter.

The figure of the drawing, which is a sectional view, illustrates two possibilities of construction; the right side may be used for coal or semi-gas fuel consumption, respectively; and the left side may beused for gas or oil fuel consumption, respectively.

The furnace comprises the known construction of the pre-heating and cooling zones (not shown) and the heating zone proper B which is disposed between the first named zones. The cars a serve the purpose of introducing the material to be treated into the furnace and they pass through the furnace from the preheating zone toward the cooling zone.

' After having passed through the pro-heating zone the cars a pass through the heating zone proper B. In the side walls of this zone several combustion chambers 3 are provided which communicate with the interior of the heating zone proper B.

144,224, and in Germany February 13, 1925.

By means of thesecombustion chambersa combustible mixture is introduced into the heatingzone which, when coming intocontact with the hot furnace walls, burns and generates the temperature necessary for annealing or heat treating the materials to be treated. The flame maybe generated either by coal, by semi-gas,,by gas, or by oil.

If 1t is contemplated to practice this invent on 1n con unction with coal fuel, then the arrangement in accordance with the right-hand side of the figure may be used. For each group ofcombus'tion chambers 3 a grate 3 is provided u on which the coal may beburned. The com ustion gases 1 which are generated take the direction represented by the arrows and are guided to the combustion chambers 3. Before reaching theheatingzone,for'1-nstance, at point 4, they are mixed with the secondary air necessary-for the combustion.

In accordance with one feature of the present inventionthe air of combustion is introduced either cold or moderately heated through ducts 5 or 5-, respectively. 1 The ducts 5 are connected with a passagewayS which extends underneath the tracks of cars a and also with the chambers 3. Branchesof these ducts5 communicate either with the outside open air or with the inside of the buildingin which the furnace is located. By means of duct, 6 hot air issupplied. By means of valves or vanes 7 ducts 5, 5 and 6 may be "partly or completely isolated. This feature enables the admixture of a gas or air whose temperature may be readily controlled to the gas current constituted by the combustion L The hot air supplied by ducts 6 istaken from the cooling zone. a In case" the present invention is to be used in conjunction with gas or oil fuel, it assumes the features represented by the left-hand side of the drawing. In this case a pipe system 2 supplies gas or vaporized oil tothe combustionchambers 3. The tankforstoringup this fuel is not shown in the drawing. The remainder of the arrangement is the same as the one described in the preceding example of execution.

We claim:

1. The method for heating furnaces which consists in generating a mixture of relatively cold air and hot air, introducing said mixture into a current of combustible gases prior to the entrance of said gases into the heating zone of the furnace, and adjusting the temperature of the mixture in such a fashion that a uniform temperature distribution within the heating zone and the production of any desired lengthof flame may be attained in the interior of said furnace.

2. The method for heating furnaces which consists in the separate introduction of a cold air current and a hot air current into the combustion gases supplied for heating the furnace at a point prior to their introduction into the furnace, characterized by the fact that .the amount and temperature of each of said aircurrents may be regulated in such a way that a uniform flame and temperature distribution in the heating zone as well as the production of any desired length of flame may be attained in the interior of the furnace.

5 3. The method of heating tunnel furnaces which consists in the separate introduction of moderately heated and hot air currents into thecombustion gases supplied for heating the furnace at a point prior to their introduction into the interior of the furnace, characterized by the fact that the amount and temperature of each of said. air currents may be regulated in such a way that a uniform flame and temperature distribution may be attained in the cheating zone proper as well as the production of any desired length of flame in the interior ,ofsaidfurnace.

, 4. 'In a tunnel furnace, a combustion chamher, a duct for introducing cold atmospheric 40 air :into said chamber, a second duct for introducing slightly heated air from a passageway, a third duct for introducing hot airfrom the cooling zone of said furnace into said .chamber, a fourth duct for introducing combustible gases into said chamber, and a Valve in each of said ducts for regulating the gas volumes entering said chamber.

5. Ina tunnel furnace, a plurality of comv bustion chambers arranged in the side walls of said furnace, a duct for each of said chambers for introducing gas, a second duct for i introducing cold air, a third duct for introducing slightly heated air from a passageway, a fourth duct for introducing hot air from the cooling zone of said furnace into said chamber, and means in each of said ducts for regulating the volumelof the gas flowing through each of said ducts. r v

In testimony whereof we have hereunto o0 aflixed our signatures.

WILHELM SCHAEFER.

WALTER POHL. 

